Chemical Management for Colorful, Efficient, and Stable Inorganic–Organic Hybrid Nanostructured Solar Cells

Coloring solar cells with simultaneously high efficiency by low-index dielectric nanoparticles

In recent years significant research has been conducted on the materials, design, and device physics of nanostructured solar cells to obtain enhanced performance. While there are several promising results, practical deployment of these nanostructured cells is quite limited due to the need for (1) cost-effective, scalable fabrication techniques; (2) readily available raw materials; and (3) cells that can reliably perform as installed with minimal performance degradation. This book chapter focuses on nanostructured silicon solar cells. Silicon has been chosen in this chapter as it is an abundantly available raw material; silicon cells are well understood due to broad deployment of conventional monocrystalline, multi-crystalline, and amorphous silicon solar cells; and silicon cells also are by far the dominant one in terms of production scale in the photovoltaic industry.The book chapter is divided into five sections and mainly focuses on nanostructured silicon-based solar cells to evaluate their potential for enhanced performance beyond conventional, commercial silicon cells. Section 1 discusses the value of nanoscale patterning in wafer-based crystalline silicon (c-Si) solar cells (e.g., mono- and multi-crystalline silicon). In Sect. 2 of the book chapter nanostructured designs that relate mainly to the electronic performance of the solar device are reviewed. In this category, nanostructured thin-film solar cells for enhanced carrier collection or enhanced internal quantum efficiency (such as nano-wire array solar cells) are illustrated. In Sect. 3 nanostructured hybrid silicon-organic solar cells are illustrated. Section 4 discusses nanostructured thin-film amorphous silicon cells for photocurrent enhancement. These designs include those that enhance the optical path length for similar or less absorber thickness as that of conventional non-structured solar cells. Nanostructured solar cells that exhibit plasmonic effects for enhanced optical absorption at wavelength ranges of interest are also discussed in some detail. Finally, nanostructured silicon quantum dot-based materials for tandem solar cells as well as nanostructured inorganic third-generation solar cells that exhibit phenomena like multiple-exciton generation, which can potentially make use of silicon-based materials, are briefly discussed. A broad background literature review of the value of nanostructuring in the major kinds of solar cell materials including silicon, III–V materials, and organic solar cells is often referenced in this book chapter and briefly discussed for the various technologies presented.In general, an attempt is made to explain the physics of the various nanostructures as well as to illustrate the processes and process conditions that were employed for the solar cell fabrication with reference to various materials and concepts used for each technology. Industrial feasibility of some of these technologies and the related challenges are also briefly discussed.KeywordsSolar CellSurface Plasmon PolaritonSilicon Solar CellSolar Cell PerformanceBlack SiliconThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Recently, antimony selenide (Sb2Se3) has been proposed as an alternative earth-abundant absorber material for thin film solar cells. Sb2Se3 is a simple V2-VI3 binary compound with an orthorhombic crystal structure and a space group of Pnma 62. It is a staggered layered compound consisting of parallel 1D (Sb4Se6)n ribbons held together by weak van der Waals forces. Sb2Se3 has a direct band gap of approximately 1.15 eV with a large absorption coefficient (>105 cm-1, at short wavelength) and a low grain growth temperature (～300^{o}C), facilitating the fabrication of low-cost thin film solar cells. Moreover, it is a simple binary compound in single phase with a fixed composition, which provides a much simpler growth chemistry than the multicomponent Cu2ZnSn(S,Se)4. In addition, it is stable upon exposure to the ambient air, thus having a better prospect for long-term stability than the organic-inorganic halide perovskite solar cells. Theoretical analysis indicates that the efficiency limit is >30% for single junction Sb2Se3 solar cells. Various approaches, including vacuum evaporation, electrodeposition, spray pyrolysis, and chemical bath deposition (CBD), have been explored to produce Sb2Se3 thin films; however, it is only in these years that Sb2Se3 solar cells have been reported by our group as well as by others. Seok's group presented the deposition of Sb2Se3 on mesoporous TiO2 films by thermal decomposition of Sb2Se3 single-source precursors, and fabricated Sb2Se3-sensitized inorganic-organic heterojunction solar cells with a remarkable efficiency of 3.21%. Tena-Zaera's group fabricated the FTO/TiO2/Sb2Se3/CuSCN/Au heterojunction device and achieved 2.1% device efficiency; their Sb2Se3 was obtained by an electrodeposition route and CuSCN served as a hole conducting layer. Different from the above Sb2Se3-sensitized solar cells reported by other groups, our group is the first in the world working on Sb2Se3 thin film solar cells so far as wu know. We have fabricated a hydrazine solution-processed TiO2/Sb2Se3 heterojunction solar cell, achieving 2.26% device efficiency (Voc = 0.52 V, Jsc = 10.3 mA/cm2 and m FF = 42.3%). In addition to the solution processing method, thermal-evaporated substrate and superstrate CdS/Sb2Se3 thin film solar cells with 2.1% and 1.9% efficiencies respectively were also demonstrated by our group. Recently, we have further improved the superstrate device performance to 3.7% (Voc=0.335 V, Jsc=24.4 mA/cm2, and m FF=46.8%$) by using a post selenization step. Selenization can compensate the Se loss during thermal evaporation, attenuate selenium vacancy-related recombination loss and hence improve the device performance. In summary, this paper summarizes the recent research progress in Sb2Se3-related researches, including material properties of Sb2Se3, synthesis of Sb2Se3 nanomaterials and thin films, theoretical studies on electrical properties, device configuration and efficiency improvement of Sb2Se3 sensitized and thin film solar cells. This review also presents a perspective on future development of Sb2Se3 solar cells.

Organometal halide perovskites have shown excellent optoelectronic properties and have been used to demonstrate a variety of semiconductor devices. Colorful solar cells are desirable for photovoltaic integration in buildings and other aesthetically appealing applications. However, the realization of colorful perovskite solar cells is challenging because of their broad and large absorption coefficient that commonly leads to cells with dark-brown colors. Herein, for the first time, we report a simple and efficient strategy to achieve colorful perovskite solar cells by using the transparent conducting polymer (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), PEDOT:PSS) as a top electrode and simultaneously as an spectrally selective antireflection coating. Vivid colors across the visible spectrum are attained by engineering optical interference effects among the transparent PEDOT:PSS polymer electrode, the hole-transporting layer and the perovskite layer. The colored perovskite solar cells display power conversion efficiency values from 12.8 to 15.1% (from red to blue) when illuminated from the FTO glass side and from 11.6 to 13.8% (from red to blue) when illuminated from the PEDOT:PSS side. The new approach provides an advanced solution for fabricating colorful perovskite solar cells with easy processing and high efficiency.

This study aimed to synthesize Cu3BiS3 semiconductor using chemical bath deposition (CBD) method and to investigate its application on semiconductor-sensitized solar cells using mesoporous TiO2 films. The Cu3Bi1S3 semiconductor was synthesized using two-step chemical deposition onto mesoporous TiO2 film: the deposition of Bi-S and the deposition of Cu-S. The formation of Cu3Bi1S3, proved by the XRD pattern, was achieved after annealed at 350°C for 1 hour in the nitrogen atmosphere. The band gap was measured using UV-Visible spectrophotometer and found to be 1.4 eV, an optimal band gap for solar cells application. Such process was then applied to produce liquid- junction semiconductor-sensitized solar cells. The observation involved were the dependence of solar cells on the use of different electrolytes, different solar cells' structure, different particle sizes of mesoporous TiO2 film and different deposition time. The best solar cell obtained has power conversion efficiency (PCE) of 0.139% with current density of 6.09 mA/cm2. This result indicates that CBD method can be used to synthesize Cu3BiS3 semiconductor into mesoporous TiO2 and further study needs to be done to search for the best solar cells' structure to obtain higher PCE from Cu3BiS3 semiconductor.

Optical Performance of Colored Crystalline Solar Cells for Building Energy Efficient Application

Dual-Resistance of Ion Migration and Moisture Erosion via Hydrolytic Crosslinking of Siloxane Functionalized Poly(Ionic Liquids) for Efficient and Stable Perovskite Solar Cells

High-performance methylammonium-free ideal-band-gap perovskite solar cells

Gradient band gap perovskite films with multiple photoluminescence peaks

ABX3 Perovskites for Tandem Solar Cells

Decoupling the effects of defects on efficiency and stability through phosphonates in stable halide perovskite solar cells

In the world of photovoltaics (PV), carbonaceous materials found to be an emerging candidate for the next generation thin film solar cell devices: organic solar cells (OSCs), perovskite solar cells (PSCs) and dye-sensitized solar cells (DSSCs). With the potential to obtain an extreme low-cost fabrication at higher power conversion efficiency, carbonaceous materials have attracted greater attention since decades ago in the important application in energy conversion systems including solar cells and fuel cells. Moreover, they exhibit higher conductivity, higher specific surface area, high transparency in the entire visible spectrum and high mechanical flexibility. In this chapter, we extant a concise outline on the importance and exciting modifications of carbon (0-dimensional quantum dots to 3-dimensional carbon black) and its derivative materials for the third generation PV cells in an effort to enhance both the device efficiency and its long-term lifetime. Herein, we have also made a brief discussion on the present progress and future challenges of carbonaceous materials in various PV technology including material synthesis, material properties, device structure and device performances that has been established in the recent reported works. To conclude, we summarized the future prospect toward achieving a higher efficient and long-term stable third generation solar cells utilizing the benefits of carbonaceous materials.

Nanostructures have been widely used in solar cells due to their extraordinary optical management properties. However, due to the poor junction quality and large surface recombination velocity, typical nanostructured solar cells are not efficient. Here we demonstrate a new approach to design and fabricate whole-wafer nanostructures on dielectric layer for solar cell application. The design, simulation, fabrication and characterization of nanostructured dielectric layer silicon solar cells are presented. The optical simulation results illustrate that the periodic nanostructure array on dielectric materials suppresses the reflection and enhances the absorption over a wide spectral range. Reflection measurements show that reflection can be suppressed below 10% for a wide range of solar spectrum and incident angle. The current density-voltage (J-V) characterization shows that the short circuit current is improved by 44%. Our results suggest this nanostructured dielectric layer has the potential to significantly improve solar cell performance and avoid typical problems of defects and surface recombination for nanostructured solar cells, thus providing a new pathway towards realizing high-efficiency and low-cost solar cells.

A major advance in the development of inorganic sensitizers of new types occurred in 2012: Park and Grätzel reported thin-film solid-state solar cells attaining PCE 9.7 % with a methyl ammonium lead-iodide perovskite sensitizer, CH3NH3PbI3, in a mesoporous TiO2 film (thickness 0.6 μm).1 This perovskite sensitizer has a bandgap 1.5 eV and V OC of this perovskite-sensitized solar cell was much greater than that of a dye-sensitized solar cell (DSSC), rendering this photovoltaic system promising for further investigations. At nearly the same time, Snaith and co-workers reported a similar perovskite, CH3NH3PbI2Cl, that served as light absorber for mesoscopic thin-film solid-state solar cells to attain PCE 10.9 %,2 for which the mesoporous Al2O3 film served as a scaffold to replace the n-type TiO2 electron-transporting layer. In 2013, Snaith and co-workers reported a significantly enhanced PCE 12.3 % for perovskite CH3NH3PbI3-x Cl x solar cells with the same device structure based on Al2O3.3 Concurrently the development of all solid-state mesoscopic solar cells has reached a new milestone when Grätzel,4 Snaith,5 Kelly6 and their co-workers reported the perovskite-based solar cells with PCE exceeding 15 % using spiro-OMeTAD as hole transporting material. Recently, we have demonstrated that perovskite solar cells using mesoporous NiO nanocrystals as p-contact electrode material in a device configuration NiO/perovskite/PCBM attained PCE 9.5 %, giving promising perspective for further development of all-inorganic perovskite-based thin-film solar cells and tandem photovoltaics. The great discovery of the perovskites as novel photovoltaic materials has hence opened a new channel for the development of third-generation solar cells with advantages of great efficiency, cheapness, ease of processing and great endurance. Both n-type and p-type perovskite solar cells will be introduced based on varied structural configurations of the devices. 1 Kim, H. S.; Lee, C. R.; Im, J. H.; Lee, K. B.; Moehl, T.; Marchioro, A.; Moon, S. J.; Humphry-Baker, R.; Yum, J. H.; Moser, J. E.; Grätzel, M.; Park, N. G. Scientific Reports 2012, 2, 591. 2 Lee, M. M.; Teuscher, J.; Miyasaka, T.; Murakami, T. N.; Snaith, H. J. Science 2012,338, 643. 3 Ball, J. M.; Lee, M. M.; Hey, A.; Snaith, H. J. Energy Environ. Sci. 2013, 6, 1739. 4 Burschka, J.; Pellet, N.; Moon, S. J.; Humphry-Baker, R. ; Gao, P.; Nazeeruddin, M. K.; Grätzel, M. Nature 2013, 499, 316. 5 Liu, M.; Johnston, M. B.; Snaith, H. J. Nature 2013, 501, 395. 6 Liu, D.; Kelly, T. L. Nature Photon. 2014, 8, 133.

Theoretical studies of ultra-thin silicon solar cells with cylindrical, conical and parabolic surface nanostructures inherited from natural self-assembled anodic alumina oxide (NSA-AAO) were performed by finite-difference time-domain (FDTD) method. All nanostructured solar cells obtained an optimized efficiency enhancement as high as more than 33% comparing with that of the anti-reflective (AR) one. Numerical results reveal that the range of efficient structural parameters for the nanostructured (e.g., cylindrical) solar cell can be effectively enlarged as the period of the nanostructure changes from 0.1 μm to 0.5 μm. Moreover, the improvements of absorption photocurrent density (Jph) in conical and parabolic nanostructured solar cells are comparable with the cylindrical nanostructured one but less sensitive to the fill factor and structural height in the whole simulation region of 0.1–0.9 and 0–0.25 μm, respectively. Equivalent refractive index models were used to analysis the antireflection performance of surface nanostructures from the point of view of sidewall profiles. Resonance modes induced through nanostructures have greatly improved the absorptance of solar cells in broadening wavelength bands which consequently raised the Jph. This study serves as a way for the practical design and application of AAO nanostructure based high-efficiency ultra-thin solar cells.